Fluid-jet precision-dispensing device having one or more holes for passing gaseous bubbles, sludge, and/or contaminants during priming

ABSTRACT

A fluid-jet precision-dispensing device includes a layer, one or more first holes within the layer, and one or more second holes within the layer. The first holes are adapted to pass fluid therethrough during usage of the device to precisely dispense the fluid at accurately specified locations. The second holes are adapted to not pass the fluid therethrough during usage of the device to precisely dispense the fluid at the accurately specified locations. The second holes may be adapted to at least substantially maximally pass gaseous bubbles therethrough during performance of a priming operation of the device. The second holes may be adapted to at least substantially maximally pass sludge and/or contaminants therethrough during performance of the priming operation of the device.

RELATED APPLICATIONS

The present application is a continuation-in-part of the previouslyfiled patent application entitled “air management in a fluid ejectiondevice,” filed Jun. 18, 2004, and assigned Ser. No. 10/872,215, now U.S.Pat. No. 7,625,080.

BACKGROUND

A common way to form images on media, such as paper, is to use afluid-ejection device, such as an inkjet-printing device. Aninkjet-printing device has a number of inkjet-printing mechanisms, suchas inkjet printhead assemblies. Each inkjet printhead assembly has aprinthead die having a number of inkjet nozzles that eject ink, such asdifferently colored ink, in such a way as to form a desired image on themedia.

A printhead assembly can be prone to the formation or inclusion ofgaseous bubbles, sludge, and/or contaminants therewithin. To ensure thatsuch gaseous bubbles, sludge, and contaminants do not affect imagequality during image formation, priming may be periodically performed.Priming desirably expels any gaseous bubbles and removes any sludge andcontaminants.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a diagram of a representative inkjet-printing device,according to an embodiment of the present disclosure.

FIG. 2 is a diagram of an inkjet printhead, according to an embodimentof the present disclosure.

FIG. 3 is a diagram of a portion of an inkjet printhead, according to anembodiment of the present disclosure.

FIG. 4 is a diagram of a portion of an inkjet printhead duringperformance of a priming operation, according to an embodiment of thepresent disclosure.

FIGS. 5, 6, 7, and 8 are diagrams depicting the locational positioningof holes within an inkjet printhead, according to varying embodiments ofthe present disclosure.

FIG. 9 is a graph depicting the relationship between flow rate andpressure for a design of an inkjet printhead, by which the placement andsize of holes within the printhead can be determined, according to anembodiment of the present disclosure.

DETAILED DESCRIPTION

FIG. 1 shows a representative inkjet-printing device 100, according toan embodiment of the present disclosure. The inkjet-printing device 100is a device, such as a printer, that ejects ink onto media, such aspaper, to form images, which can include text, on the media. Theinkjet-printing device 100 is more generally a fluid-jetprecision-dispensing device that precisely dispenses fluid, such as ink,as is described in more detail later in the detailed description.

The inkjet-printing device 100 may eject pigment-based ink, dye-basedink, or another type of ink. Differences between pigment-based inks anddye-based inks can include that the former may be more viscous than thelatter, among other differences. In these and other types of ink, theink may be generally considered as having at least a liquid component,and may also have a solid component in the case of pigment-based inks inparticular. The liquid component may be water, alcohol, and/or anothertype of solvent or other type of liquid, whereas the solid component maybe pigment, or another type of solid.

While the detailed description is at least substantially presentedherein to inkjet-printing devices that eject ink onto media, those ofordinary skill within the art can appreciate that embodiments of thepresent disclosure are more generally not so limited. In general,embodiments of the present disclosure pertain to any type of fluid-jetprecision-dispensing device that dispenses a substantially liquid fluid.A fluid-jet precision-dispensing device is a drop-on-demand device inwhich printing, or dispensing, of the substantially liquid fluid inquestion is achieved by precisely printing or dispensing in accuratelyspecified locations, with or without making a particular image on thatwhich is being printed or dispensed on. As such, a fluid-jetprecision-dispensing device is in comparison to a continuousprecision-dispensing device, in which a substantially liquid fluid iscontinuously dispensed therefrom. An example of a continuousprecision-dispensing device is a continuous inkjet-printing device, forinstance.

The fluid-jet precision-dispensing device precisely prints or dispensesa substantially liquid fluid in that the latter is not substantially orprimarily composed of gases such as air. Examples of such substantiallyliquid fluids include inks in the case of inkjet-printing devices. Otherexamples of substantially liquid fluids include drugs, cellularproducts, organisms, fuel, and so on, which are not substantially orprimarily composed of gases such as air and other types of gases, as canbe appreciated by those of ordinary skill within the art. Therefore,while the following detailed description is described in relation to aninkjet-printing device that ejects ink onto media, those of ordinaryskill within the art will appreciate that embodiments of the presentdisclosure more generally pertain to any type of fluid-jetprecision-dispensing device that dispenses a substantially liquid fluidas has been described in this paragraph and the preceding paragraph.

FIG. 2 shows a detailed view of an inkjet printhead 400, according to anembodiment of the present disclosure. The inkjet printhead 400 is moregenerally a cartridge or a cartridge assembly, and most generally afluid-jet precision-dispensing device cartridge assembly. Referencenumber 408 denotes the x-, y-, and z-axes in FIG. 2. The inkjetprinthead 400 is more generally a fluid-ejection mechanism, in that itis the actual mechanism that ejects fluid, such as ink, onto media toform images on the media. The inkjet printhead 400 may also be referredto as an inkjet printing device printhead assembly, or just an inkjetprinthead assembly. The inkjet printhead 400 may further be referred toas simply a device, such as a fluid-jet precision-dispensing device,where the terminology “device” is used herein in a general sense.

The inkjet printhead 400 is inserted into the inkjet-printing device100. There may be one or more such inkjet printheads that are insertedinto the inkjet-printing device 100. Each inkjet printhead may havesupplies of one or more differently colored inks, such as black ink,cyan ink, magenta ink, yellow ink, as well as other colored inks. Inanother embodiment, the inkjet printheads do not contain supplies ofink, such that there can be one or more inkjet cartridges that containsupplies of inks, and that are separate from the inkjet printheads.

The inkjet printhead 400 is depicted in FIG. 2 as including a housing402, a printhead die 404, and a flexible circuit 406. The printhead die404 is more generally a fluid-jet precision-dispensing device die, andmay most simply be referred to as a fluid-jet precision-dispensingdevice as well, where the terminology “device” is used in its mostgeneral sense. Those of ordinary skill within the art can appreciatethat the inkjet printhead 400 may include other components in additionto those depicted in FIG. 2.

The printhead die 404 is attached or otherwise disposed to the housing402. The printhead die 404 includes a number of inkjet nozzles thateject ink, such as differently colored ink. The inkjet nozzles of theprinthead die 404 are not particularly called out in FIG. 2.Furthermore, the flexible circuit 406 bends at an edge of the housing402, such that the flexible circuit 406 is wrapped around the housing402.

A first portion 412 of the flexible circuit 406 is electrically coupledto the printhead die 404 at ends of the die 404. A second portion 414 ofthe flexible circuit 406 is attached to the housing 402 itself. Uponinsertion of the housing 402 of the inkjet printhead 400 into an inkjetprinting device, the second portion 414 of the flexible circuit 406makes electrical contact with the inkjet printing device. In this way,the flexible circuit 406 electrically couples the inkjet printing devicewith the printhead die 404 so that the printing device is able tocontrol ejection of ink from the die 404.

FIG. 3 shows a portion of the inkjet printhead 400 in more detail,according to an embodiment of the present disclosure. Reference number501 denotes the x-, y-, and z-axes in FIG. 3. The inkjet printhead 400includes chamber sidewalls 502 that define a chamber 504 to which inkcan be supplied. The chamber 504 is capped by the printhead die 404.That is, the chamber 504 ends at one side thereof at the printhead die404 (and it can be said that the chamber 504 ends at any layer of thedie 404 in this respect). In one embodiment, the printhead die 404 maybe considered as having at least two layers 506 and 510. However, inother embodiments, the die 404 may have fewer or greater layers than twolayers as depicted in FIG. 3. Additionally, those of ordinary skillwithin the art can appreciate that each of the layers 506 and 510 mayitself be made up of more than one layer.

The layer 506 defines a number of inlet holes 512 that permit the inkwithin the chamber 504 to pass from the chamber 504 to the printhead die404. Situated at or part of the layer 506 are a number of fluid-ejectionelements 514, such as heating elements like resistive heating elements,piezo elements such as piezo-electric elements, as well as other typesof fluid-ejection elements. Furthermore, the layer 510 may be referredto as an orifice plate. The layer 510 defines a number of holes 516 anda number of holes 518. The holes 516 may be referred to as first holesand the holes 518 may be referred to as second holes to distinguish theholes 516 from the holes 518. Furthermore, the first holes 516 may bereferred to as the inkjet nozzles of the inkjet printhead 400.

As depicted in FIG. 3, the first holes 516 and the second holes 518 mayhave substantially identical profiles, such as tapered profiles as inFIG. 3. It is also noted that in one embodiment, the first holes 516 arenot located directly below or under the chamber 504 and instead arelocated directly below or under the chamber sidewalls 502, whereas thesecond holes 518 are located directly below or under the chamber 504, asopposed to directly below or under the chamber sidewalls 502. However,in another embodiment, the first holes 516 and the second holes 518 maybe both located directly below the chamber 504, or may be both locatednot directly below the chamber 504. In still another embodiment, thesecond holes 518 may be located directly below the chamber sidewalls502, while the first holes 516 may be located directly below the chamber504.

Each of the first holes 516 corresponds to one of the fluid-ejectionelements 514, such that the first holes 516 may be positioned directlyunderneath the elements 514 in one embodiment. It is noted that bycomparison, there is no fluid-ejection element 514 at any of the secondholes 518; rather, there is just a fluid-ejection element 514 at each ofthe first holes 516 in the embodiment of FIG. 3. During usage of theinkjet printhead 400 to form images on media (i.e., to preciselydispense fluid at accurately specified locations), when a desired firsthole 516 is to have an ink droplet ejected therefrom, the correspondingfluid-ejection element 514 is activated. Activation of thefluid-ejection element 514 ultimately causes an ink droplet to beejected from the corresponding first hole 516.

For example, in a particular embodiment in which the fluid-ejectionelements 514 are resistive heating elements, activation of afluid-ejection element 514 means that a sufficient current is passedthrough the element 514 to heat the element 514. As such, the ink aroundthe fluid-ejection element 514 in question at least substantially boils,forming a small gaseous bubble within this ink. The bubble in turnforcibly ejects a droplet of ink through the corresponding first hole516.

Therefore, during usage of the inkjet printhead 400 to form images onmedia (i.e., to precisely dispense fluid at accurately specifiedlocations), ink passes through the first holes 516, such that it can besaid that the first holes 516 are adapted to pass such fluidtherethrough during such usage of the printhead 400. By comparison,during usage of the printhead 400 to form images on media (i.e., toprecisely dispense fluid at accurately specified locations), ink doesnot pass through the second holes 518. Therefore, it can be said thatthe second holes 518 are adapted to not pass such fluid therethroughduring such usage of the printhead 400.

It is noted, however, that in another embodiment, there may befluid-ejection elements at one or more of the second holes 518. In suchan embodiment, the fluid-ejection elements at the second holes 518 arenot employed during usage of the inkjet printhead 400 to form images onmedia (i.e., to precisely dispense fluid at accurately specifiedlocations). Rather, the fluid-ejection elements at the second holes 518are employed during performance of priming operations, which aredescribed in more detail later in the detailed description, to assist ineject ink during from these second holes 518 during such primingoperations.

In general, the second holes 518 are adapted to not pass inktherethrough during usage of the inkjet printhead 400 to form images onmedia (i.e., to precisely dispense fluid at accurately specifiedlocations) by having critical pressures that have absolute values whichare greater than (i.e., or otherwise appropriate to) absolute values ofthe backpressures at the second holes 518. The critical pressure is thepressure at which the meniscus of fluid at a second hole 518 isdetached, initiating the flow of ink, air, sludge, and/or contaminantsthrough the second hole 518 in question. By ensuring that the criticalpressure at each second hole 518 is greater in absolute value than(i.e., or otherwise appropriate to) the absolute value of thebackpressure experienced during usage of the inkjet printhead 400 toform images on media, it is ensured that ink does not flow through thesecond hole 518 in question during such usage of the printhead 400. Itis noted that the critical pressure as to air or other gas can beparticularly referred to as bubble pressure, whereas the terminologycritical pressure is more general, and relates more generally to ink,air, sludge, and/or contaminants.

Furthermore, ensuring that the critical pressure at each second hole 518is greater than the backpressure during usage of the inkjet printhead400 to form images on media (i.e., to precisely dispense fluid ataccurately specified locations), gas such as air is at leastsubstantially prevented from being introduced into the chamber 504through the second hole 518 in question. Ensuring that the criticalpressure at each second hole 518 is greater than the backpressure duringsuch usage of the printhead 400 can be achieved by appropriately sizingeach second hole 518. Additionally or alternatively, ensuring that thecritical pressure at each second hole 518 is greater than thebackpressure can be achieved by appropriately shaping each second hole518. For a given design of the inkjet printhead 400, the appropriatesize and/or shape of each second hole 518 in this respect can bedetermined experimentally.

FIG. 4 representatively depicts a priming operation being performed inrelation to the inkjet printhead 400, according to an embodiment of theinvention. Reference number 501 again denotes the x-, y-, and z-axes inFIG. 4. A priming operation is generally an operation in which apressure differential is actively employed, such as by attaching a cap,or a primer, 602 to the printhead 400 to form a seal around the firstholes 516 and the second holes 518. Fluid movement through the holes 516and 518 results from this pressure differential.

For example, in the specific embodiment depicted of FIG. 4, a particulartype of priming operation referred to as a suction prime is shown. In asuction prime, a negative pressure around the holes 516 and 518 iscreated by a suction or vacuum effect, as is particularly indicated bythe arrows 610. By comparison, another type of priming operation isknown as a push prime. In a push prime, a positive pressure around theholes 516 and 518 is created.

During the life of the inkjet printhead 400, gas such as air may beintroduced into the printhead 400, resulting in formation of gaseousbubbles 604. During usage of the inkjet printhead 400 to form images onmedia (i.e., to precisely dispense fluid at accurately specifiedlocations), such bubbles 604 can deleteriously affect image quality.More generally, the gaseous bubbles 604 can affect the precisedispensation of fluid at accurately specified locations.

Similarly, during the life of the inkjet printhead 400, sludge 606 maycollect, accumulate, or otherwise form within the printhead 400, due tothe drying of the ink resulting in the ink losing at least some of itsliquid component, or the ink itself changing over time. For instance,the ink may settle, flocculate, aggregate, and so on. Furthermore,during the life of the inkjet printhead 400, the ink may becomesubjected to contamination from contaminants 608 such as dust and othertypes of contaminants from both inside and outside the printhead 400. Assuch, during use of the inkjet printhead 400 to form images on media(i.e., to precisely dispense fluid at accurately specified locations),the sludge 606 and the contaminants 608 can deleteriously affect imagequality. More generally, the sludge 606 and the contaminants 608 canaffect the precise dispensation of fluid at accurately specifiedlocations.

During performance of the priming operation, the gaseous bubbles 604,the sludge 606, and the contaminants 608 are actively removed from theinkjet printhead 400. As such, image quality is subsequently notaffected when the printhead 400 is subsequently used to form images onmedia. That is, when the printhead 400 is subsequently used to preciselydispense fluid at accurately specified locations, the prior at leastsubstantial removal of the gaseous bubbles 604, the sludge 606, and thecontaminants 608 promotes optimal such precise dispensation of fluid ataccurately specified locations.

The sludge 606 may have dried in portions that are larger in size thanthe first holes 516. Therefore, in an embodiment in which the secondholes 518 are larger in size than the first holes 516 are, the sludge606 is more easily removed during performance of the priming operation.For instance, the second holes 518 may be a priori sized so that theyare larger than what empirical tests reveal to be the maximum size ofthe portions of the sludge 606. As a result, removal of the sludge 606is achieved through the second holes 518 at a lower fluid flow rateresulting from the suction effect than would otherwise be needed ifremoval of the sludge 606 were achieved through the first holes 516.Indeed, such larger portions of the sludge 606 may otherwise undesirablyplug the first holes 516 during performance of the priming operation butfor the presence of the second holes 518.

Sizing the second holes 518 larger than the first holes 516 also canimprove removal of the gaseous bubbles 604 from the inkjet printhead400, at least insofar as there are more routes available for the bubbles604 to be removed from the printhead 400 when the second holes 518 arepresent in addition to the first holes 516 being present. Otheradvantages and aspects of embodiments of the present disclosure that areassociated with having the second holes 518 present during performanceof the priming operation are discussed later in the detaileddescription. In general, however, the second holes 518 can be said to beadapted to at least substantially maximally pass the gaseous bubbles604, the sludge 606, and/or the contaminants 608 therethrough duringperformance of the priming operation.

FIG. 5 shows how the first holes 516 and the second holes 518 may belocated on the layer 510 of the inkjet printhead 400, according to anembodiment of the present disclosure. Reference number 702 denotes thex-, y-, and z-axes in FIG. 5. The first holes 516 are positionallyarranged in two columns over the long side of the layer 510, parallel tothe x-axis. (It is noted that the arrangements of the holes 516 and 518depicted in FIG. 5 and the other figures are particular to specificembodiments, while in other embodiments other arrangements of the holes516 and 518 may be achieved.) In general, the distance between the firstof the first holes 516 and the last of the first holes 516 within eitherof the two columns corresponds to the swath of the printhead 400, whichis the distance over which ink can be ejected without having to move theprinthead 400 or the media along the x-axis.

It has been determined that for many designs of inkjet printheads,gaseous bubbles, sludge, and/or contaminants tend to migrate to one sideof a given printhead or the other side of the printhead along thex-axis. Therefore, in the embodiment of FIG. 5, the second holes 518 arepositionally located at or towards the side of the printhead 400 atwhich gaseous bubbles, sludge, and/or contaminants tend to migrate. Thisis advantageous, as it decreases the amount of ink (i.e., fluid) that isused during performance of the priming operation, and/or the duration ofthe priming operation.

That is, if gaseous bubbles, sludge, and/or contaminants tend to migrateto just one side of the printhead 400 along the x-axis, but if thesecond holes 518 are positioned over both sides, the net effect is thatthe priming operation results in more ink being used than may be needed.Because the priming operation is intended to remove gaseous bubbles,sludge, and/or contaminants, strategically locating the second holes 518on the side where it has been empirically determined that these bubbles,sludge, and/or contaminants tend to migrate reduces the amount of inkexpunged from the printhead 400 during performance of the primingoperation.

FIG. 6 shows how the first holes 516 and the second holes 518 may belocated on the layer 510 of the inkjet printhead 400, according toanother embodiment of the present disclosure. Reference number 702 againdenotes the x-, y-, and z-axes in FIG. 6. The first holes 516 can bepositionally arranged in two columns over the long side of the layer510, parallel to the x-axis. The length of the layer 510, denoted by theletter L in FIG. 6, is longer than the length of the layer 510 in FIG.5. This can be advantageous, as it provides for a larger swath of theprinthead 400, which generally equates to faster printing. The layer 510may thus be considered a long layer.

A general disadvantage of having such a long layer 510 as in FIG. 6 isthat it has been determined that, in general, performance of the primingoperation has to occur at a relatively high fluid flow rate of ink fromthe inkjet printhead 400 where the second holes 518 are not present. Arelatively high fluid flow rate is disadvantageous because it increasesthe amount of fluid that is used during performance of the primingoperation. However, the presence of the second holes 518 has been foundto permit performance of the priming operation to be able to occur at alower fluid flow rate of ink from the inkjet printhead 400. As such, theamount of fluid used during performance of the priming operation isdecreased.

In particular, the size, shape, and/or number of the second holes 518can be empirically tested to provide for the lowest fluid flow rate ofink from the inkjet printhead 400 during performance of the primingoperation, while still providing for satisfactory removal of gaseousbubbles, sludge, and/or contaminants. A lower fluid flow rate isgenerally achieved by decreasing the pressure against the layer 510during performance of the priming operation. This is also advantageousbecause it at least substantially prevents additional gas from beingintroduced into the printhead 400 elsewhere.

For example, if the negative pressure against the layer 510 is too greatduring performance of the priming operation, gas may be suctioned intothe inkjet printhead 400 at fluid interconnect interfaces and at otherlocations around the printhead 400. As such, while gaseous bubbles maybe removed from the printhead 400 during such priming, further gaseousbubbles are inadvertently and nevertheless formed. Therefore, thepresence of the second holes 518, by permitting the negative pressureagainst the layer 510 to be lowered during performance of the primingoperation, at least substantially ameliorates this problem.

FIG. 7 shows how the first holes 516 and the second holes 518 may belocated on the layer 510 of the inkjet printhead 400, according to stillanother embodiment of the present disclosure. Reference number 702 asbefore denotes the x-, y-, and z-axes in FIG. 7. The first holes 516 areas before positionally arranged in two columns over the long side of thelayer 510, parallel to the x-axis. The length of the layer 510, againdenoted by the letter L in FIG. 7, is shorter than the length of thelayer 510 in FIG. 5. This can be advantageous, in that it may be lessexpensive to manufacture shorter printheads. The layer 510 may thus beconsidered a short layer.

A general disadvantage of having such a short layer 510 as in FIG. 7 isthat it has been determined that, in general, performance of the primingoperation takes a relatively long length of time to complete, due to therelatively low fluid flow rate of ink from the inkjet printhead 400where the second holes 518 are not present. A relatively low fluid flowrate is disadvantageous because it causes the priming operation to takea long time to complete. However, the presence of the second holes 518has been found to improve performance of the priming operation bydecreasing the length of time in which priming is completed, due to thefluid flow rate increasing as a result of the second holes 518.

In particular, the size, shape, and/or number of the second holes 518can be empirically tested to provide for an increased fluid flow rate ofink from the inkjet printhead 400, while still not resulting in asufficiently high fluid flow rate that results in the disadvantagesdescribed in relation to FIG. 6 above. In one embodiment, for instance,the second holes 518 may be rectangularly shaped, as is specificallyshown in FIG. 7. Rectangular holes 518 can be advantageous over roundholes 518 in that they provide for an increased flow rate through thesecond holes 518 during performance of the priming operation withoutdecreasing the critical pressure at each second hole 518. Other types ofshapes of the second holes 518 can include stars, triangles, ovals, andso on.

FIG. 8 shows how the first holes 516 and the second holes 518 may belocated on the layer 510 of the inkjet printhead 400, according toanother embodiment of the present disclosure. Reference number 702denotes the x-, y-, and z-axes in FIG. 8. The first holes 516 arepositionally arranged around the circumference of an imaginary circle802. By comparison, the second holes 518 are positionally arrangedwithin a center of the circle 802.

FIG. 9 shows a graph 900 depicting the relationship between flow rateand pressure, which can be used to properly design the number and sizeof the second holes 518 within the inkjet printhead 400, according to anembodiment of the present disclosure. The x-axis 904 denotes flow rate,while the y-axis 906 denotes the pressure differential across the layer510 of the inkjet printhead 400. The horizontal line 908 defines acritical pressure-limited region 912; any pressure below the horizontalline 908 is below the critical pressure for any given flow rate. Bycomparison, the vertical line 910 defines a critical flow rate-limitedregion 910; any flow rate to the left of the vertical line 910 is belowthe critical flow rate for any given pressure. The critical flow rate isa flow rate at which fluid, air, sludge, and contaminants move throughthe first holes 516 and/or the second holes 518.

Furthermore, the horizontal line 908 and the vertical line 910 togetherdefine an ideal region 916. Any flow rate to the right of the verticalline 910 at any pressure above the horizontal line 908 permits fluid,air, sludge, and/or contaminants to move through the first holes 516and/or the second holes 518 without realizing a pressure below thecritical pressure. Thus, for a given critical flow rate denoted by thevertical line 910, there is an ideal relationship between flow rate andpressure denoted by the line 918. The intersection point 920 of thelines 908 and 910 particularly denotes the lowest pressure and flow ratecombination to move fluid, air, sludge, and/or contaminants to movethrough the first holes 516 and/or the second holes 518.

The flow rate-pressure characteristics of two example designs of theinkjet printhead 400 having first holes 516 within the layer 500—priorto the inclusion of second holes 518—are depicted in FIG. 9 by the lines922 and 924. The line 922 represents an example design that is flowrate-limited, insofar as the line 922 crosses the vertical line 910after it crosses the horizontal line 908 when starting at the origin ofthe graph 902. By comparison, the line 924 represents an example designthat is pressure-limited, insofar as the line 924 crosses the horizontalline 908 after it crosses the vertical line 910 when starting at theoriginal of the graph 902.

Thus, the purpose of adding the second holes 518 varies between the flowrate-limited design represented by the line 922 and the pressure-limiteddesign represented by the line 924. In the flow-rate limited designrepresented by the line 922, the second holes 518 may be added toincrease flow at lower pressures, to decrease the slope of the line 922to approach the ideal relationship between flow rate and pressuredenoted by the line 918. By comparison, in the pressure-limited designrepresented by the line 924, the second holes 518 may be added todecrease the critical pressure, thereby decreasing the required flowrate, and to increase the slope of the line 924 to approach the idealrelationship between flow rate and pressure denoted by the line 918.

Embodiments of the present disclosure have been described in which thelocation, size, shape, and number of the second holes 518 can be variedto achieve optimal removal of gaseous bubbles, sludge, and contaminantsfrom the printhead 400 during performance of the priming operation.Depending on where the gaseous bubbles, sludge, and contaminants aredetermined to typically migrate, for instance, the location of thesecond holes 518 can be correspondingly placed after empirical testing.Depending on whether the printhead 400 is long or short, for instance,the size, shape and number of the second holes 518 can be specifiedafter empirical testing to decrease or increase fluid flow rate, asdesired, during performance of the priming operation. Finally, it isnoted that the first holes 516 and the second holes 518 may beconsidered as particular means for performing their respectivefunctionalities described herein.

We claim:
 1. A fluid-jet precision-dispensing device comprising: a firstlayer defining a first chamber; a second layer defining a second chamberbelow the first chamber, the second chamber fluidically coupled to thefirst chamber, the second chamber having a lesser height than the firstchamber and a greater width than the first chamber; one or moreactuators within the second layer; one or more first holes within thesecond layer and opposite the one or more actuators, the first holesadapted to pass fluid therethrough upon ejection by the actuators duringusage of the device to precisely dispense the fluid at accuratelyspecified locations; and, one or more second holes within the secondlayer, the second holes adapted to not pass the fluid therethroughduring usage of the device to precisely dispense the fluid at theaccurately specified locations, the second holes further adapted to oneor more of: pass gaseous bubbles therethrough during performance of apriming operation of the device; and, pass sludge and/or contaminantstherethrough during performance of the priming operation of the device,wherein the second holes are sized and/or shaped to ensure that acritical pressure at each second hole has an absolute value greater thanan absolute value of a backpressure at each second hole during the usageof the device.
 2. The device of claim 1, wherein the priming operationof the device comprises formation of a seal around the first holes andthe second holes and actively moving fluid through the first holesand/or the second holes to at least substantially remove the gaseousbubbles, sludge, and/or the contaminants.
 3. The device of claim 1,wherein the gaseous bubbles, the sludge, and/or the contaminants migrateto one side of the layer, such that the second holes are located at theone side of the layer, to decrease an amount of fluid used duringperformance of the priming operation of the device and/or a duration ofthe priming operation.
 4. The device of claim 1, wherein the secondholes are sized, shaped, and/or numbered to decrease a flow of the fluidduring performance of the priming operation of the device to one or moreof: decrease an amount of fluid used during performance of the primingoperation of the device; and, at least substantially prevent additionalgas from being introduced into the device.
 5. The device of claim 1,wherein the second holes are sized, shaped, and/or numbered to increasea flow rate of the fluid during performance of the priming operation ofthe device to improve performance of the priming operation.
 6. Thedevice of claim 1, wherein the second holes are larger in size than thefirst holes are, such that performance of the priming operation resultsin one or more of: at least substantial removal of the sludge and/or thecontaminants through the second holes without the sludge plugging thefirst holes; and, improved removal of the gaseous bubbles from thedevice.
 7. The fluid-jet precision-dispensing device of claim 1, whereinthe first holes and the second holes are asymmetrically positioned inrelation to the first chamber.
 8. The fluid-jet precision-dispensingdevice of claim 1, wherein the second layer includes a post centrallydividing a first half of the second chamber from a second half of thesecond chamber, the one or more first holes and the one or more secondholes located in the first half of the second chamber, the first holesand the second holes asymmetrically positioned in relation to the firstchamber.
 9. The fluid-jet precision-dispensing device of claim 8,further comprising one or more third holes of a same type as the firstholes, and one or more fourth holes of a same type as the second holes,the third holes and the fourth holes located in the second half of thesecond chamber in a mirrored relationship with respect to the firstholes and the second holes.
 10. A fluid-jet precision-dispensing devicecomprising: a first layer defining a first chamber; a second layerdefining a second chamber below the first chamber, the second chamberfluidically coupled to the first chamber, the second chamber having alesser height than the first chamber and a greater width than the firstchamber; one or more actuators within the second layer; one or morefirst holes within the second layer and opposite the one or moreactuators, the first holes adapted to pass fluid therethrough uponejection by the actuators during usage of the device to preciselydispense the fluid at accurately specified locations; one or more secondholes within the second layer and not opposite the one or moreactuators, the second holes adapted to not pass the fluid therethroughduring usage of the device to precisely dispense the fluid at theaccurately specified locations, the second holes further adapted to oneor more of: pass gaseous bubbles therethrough during performance of apriming operation of the device; and, pass sludge and/or contaminantstherethrough during performance of the priming operation of the device.11. The fluid-jet precision-dispensing device of claim 10, wherein thefirst holes and the second holes are asymmetrically positioned inrelation to the first chamber.
 12. The fluid-jet precision-dispensingdevice of claim 10, wherein the second layer includes a post centrallydividing a first half of the second chamber from a second half of thesecond chamber, the one or more first holes and the one or more secondholes located in the first half of the second chamber, the first holesand the second holes asymmetrically positioned in relation to the firstchamber.
 13. The fluid-jet precision-dispensing device of claim 12,further comprising one or more third holes of a same type as the firstholes, and one or more fourth holes of a same type as the second holes,the third holes and the fourth holes located in the second half of thesecond chamber in a mirrored relationship with respect to the firstholes and the second holes.
 14. A fluid-jet precision-dispensing devicecomprising: a housing; one or more cartridges insertable into thehousing, each cartridge comprising: a first layer defining a firstchamber; a second layer defining a second chamber below the firstchamber, the second chamber fluidically coupled to the first chamber,the second chamber having a lesser height than the first chamber and agreater width than the first chamber;  one or more actuators within thesecond layer; one or more first holes within the second layer andopposite the one or more actuators, the first holes adapted to passfluid therethrough upon ejection by the actuators during usage of thedevice to precisely dispense the fluid at accurately specifiedlocations; and,  one or more second holes within the second layer, thesecond holes adapted to not pass the fluid therethrough during usage ofthe device to precisely dispense the fluid at the accurately specifiedlocations, the second holes further adapted to one or more of: passgaseous bubbles therethrough during performance of a priming operationof the device; and, pass sludge and/or contaminants therethrough duringperformance of the priming operation of the device, wherein the secondholes are sized and/or shaped to ensure that a critical pressure at eachsecond hole has an absolute value greater than an absolute value of abackpressure at each second hole during the usage of the device.
 15. Thefluid-jet precision-dispensing device of claim 14, wherein the firstholes and the second holes are asymmetrically positioned in relation tothe first chamber.
 16. The fluid-jet precision-dispensing device ofclaim 14, wherein the second layer includes a post centrally dividing afirst half of the second chamber from a second half of the secondchamber, the one or more first holes and the one or more second holeslocated in the first half of the second chamber, the first holes and thesecond holes asymmetrically positioned in relation to the first chamber.17. The fluid-jet precision-dispensing device of claim 16, wherein eachcartridge further comprises one or more third holes of a same type asthe first holes, and one or more fourth holes of a same type as thesecond holes, the third holes and the fourth holes located in the secondhalf of the second chamber in a mirrored relationship with respect tothe first holes and the second holes.